a. Field of the Invention
The instant invention is directed toward catheter systems and methods for anchoring the catheter in tissue, e.g., for delivery of a biologic or chemical agent, or other therapeutic fluid. In particular, the catheter of the present invention comprises anchoring means which may be used to anchor the catheter system to the tissue, fluid delivery means for delivery of a biologic or chemical agent, or other therapeutic fluid to the tissue, and means for tissue contact assessment during these procedures.
b. Background Art
Normal heart rhythm is between 60 and 100 beats per minute. Tachycardia is a fast heart rate (usually over 100 beats per minute) caused by disease or injury. Tachycardias may begin in the upper chambers of the heart (the atria) or the lower chambers of the heart (the ventricles). Some tachycardias are harmless, but other tachycardias are life threatening. Tachycardias can deteriorate to fibrillation, a disorder in which, the heart does not move enough blood to meet the needs of the body.
Atrial fibrillation (AF) is the most common abnormal heart rhythm. It is a very fast, uncontrolled heart rhythm that occurs when the upper chambers of the heart (the atria) try to beat so fast between 350 and 600 times per minute) that they only quiver. Ventricular fibrillation (VF) occurs when the lower chambers of the heart (the ventricles) produce fast and erratic electrical impulses that fail to induce synchronous mechanical contraction, such that oxygenated blood is not circulated through the body. Fibrillation in the ventricles is a life-threatening arrhythmia demanding immediate treatment.
Before a tachycardia deteriorates to fibrillation, various procedures may be used to treat the heart tissue and reduce or altogether eliminate the occurrence of fibrillations. It is well known that treatment benefits may be gained by delivering biologic or chemical agents, or other therapeutic fluid to heart tissue if the depth and location of delivery can be controlled. For example, chemical agents may be used to create lesions in tissue, which change the electrical properties of the tissue. For example, when lesions are formed at specific locations in cardiac tissue, undesirable atrial fibrillations may be lessened or eliminated. Likewise, biologic and chemical agents may be delivered into infracted tissue in the lower chambers of the heart (the ventricles) to promote angiogenesis for the treatment of Ventricular Tachycardia (VT). Other procedures are also known for treating these and other ailments. Use of particular biologic or chemical agents, or other therapeutic fluid depends at least to some extent on the procedure, desired treatment. and may also depend on other considerations, such as tissue characteristics.
Several difficulties may be encountered, however, when attempting to deliver biologic or chemical agents, or other therapeutic fluid at specific locations in the tissue using some existing catheters. For example, establishing and maintaining adequate tissue contact during the procedure is not always readily achieved. Typically, the physician determines tissue contact based on his/her experience maneuvering the catheter. Such experience only comes with time, and may be quickly lost if the physician does not perform the procedure on a regular basis. When used inside the heart, the beating heart further complicates matters by making it difficult to establish and maintain sufficient contact with the tissue for a sufficient length of time to deliver the desired dose of biologic or chemical agents, or other therapeutic fluid. If the contact with the tissue cannot be properly maintained during the procedure, the procedure may be unsuccessful and may need to be repeated. In ablation procedures, for example, the amount of contact is critical to form sufficiently deep ablative lesions on the tissue without damaging surrounding tissue in the heart.
Thus, there remains a need for establishing and maintaining tissue contact during a procedure for delivery of biologic or chemical agents, or other therapeutic fluid.